A combustor is usually provided in gas turbine engines to define a combustion chamber for a combustion reaction taking place therein to produce combustion gases to power the engine. The combustor is assembled with a number of combustor liners, particularly for an inner surface of the combustion chamber, which usually is referred to as a hot surface, works in an extremely elevated temperature environment. Therefore, cooling air is provided through a plurality of holes in the combustor liners referred to as effusion cooling holes, into the combustion chamber over the hot surface in order to protect the combustor liners from damage resulting from the extremely elevated temperature environment within the combustion chamber. The effusion cooling air flow passing through the effusion cooling holes in the combustor liners must be accurately determined. Excessive effusion cooling air flow not only wastes compressor air but also adversely affects the appropriate conditions for combustion reaction in the combustion chamber, which in turn adversely affects engine performance.
Accordingly, there is a need to provide an improved method for making and repairing effusion cooling holes in a combustor liner in order to achieve an effusion cooling flow which does not exceed a predetermined level.